The change of earth shape over time is expressed as Geological Evolution. The German meteorologist Alfred Wegener (1880-1930) describes the geological evolution of the Continental Drift Theory, which means that terrestrial parts of the earth and large water bodies change over time. According to the Continental Drift Theory, during the Mesozoic Era, the large earth continent Pangaea was divided into two gigantic continents (Laurasia and Gondwana), forming the Tethys Sea. The Tethys Sea was connected to the present Indian Ocean through the Atlantic Ocean and the Mediterranean Sea. A large part of Anatolia, especially in Southeastern Anatolia, was covered with the sea for a long time. Today's both Mediterranean and Black Sea is considered as a remnant of Tethys Sea. These seas were also subjected to some other important changes. In the studies carried out within the province of Diyarbakır, the biological evidences of the Tethys Sea were found in invertebrate fossils. The marine form of fossils belonging to Echinodermata and Bivalvia phyla are frequently encountered in the Southeastern Anatolia Region. They were collected from the Diyarbakır province and photographed. The fossil specimens are of great importance in terms of understanding the geological changes (Geological evolution) that the region has undergone over time.